Powertrain architectures comprise torque-generative devices, including internal combustion engines and electric machines, which transmit torque through a transmission device to a vehicle driveline. One such transmission includes a two-mode, compound-split, electro-mechanical transmission which utilizes an input member for receiving motive torque from a prime mover power source, typically an internal combustion engine, and an output member for delivering motive torque from the transmission to the vehicle driveline. Electrical machines, operatively connected to an electrical energy storage device, comprise motor/generators operable to generate motive torque for input to the transmission, independently of torque input from the internal combustion engine. The electrical machines are further operable to transform vehicle kinetic energy, transmitted through the vehicle driveline, to electrical energy potential that is storable in the electrical energy storage device. A control system monitors various inputs from the vehicle and the operator and provides operational control of the powertrain system, including controlling transmission gear shifting, controlling the torque-generative devices, and regulating the electrical power interchange between the electrical energy storage device and the electrical machines.
Engineers implementing powertrain systems having electro-mechanical transmissions are tasked with developing shifting schemes between various operating modes, including fixed gear modes and continuously variable modes. During execution of a shift into a fixed gear mode, there can be a change in operating conditions which can affect actuation of an oncoming clutch and associated driveline dynamics.
Therefore, there is a need to for a method and apparatus to control operation of a hybrid transmission during gear shifting events, to address concerns mentioned hereinabove.